Before DC vs. Heller, one of the arguments used to justify ignoring the second amendment was that it referred to a collective right, rather than an individual right. Since the Heller decision, they like to point out that it was a 5-4 decision. That is true as far as it goes, but the 5-4 split was only on the extent of the right--If you read the decision, you would see that all 9 justices recognized an individual right.
What has never been clear to me is what a collective right is, and how it would differ from no second amendment at all. There's also the 'only for militia' interpretation-which almost always denigrates the unorganized militia. Apparently in this view, the only arms protected are the ones issued by the government for militia service--and if they decide not to issue to you, tough. Again...how is this different than no right at all?